1. Field of the Invention
The present invention relates to a hyperbranched polymer, an organic light-emitting diode including an organic layer including the hyperbranched polymer, and a method of manufacturing the organic light-emitting diode. More particularly, the present invention relates to a hyperbranched polymer which has excellent hole injection capability and/or electron blocking capability and adhesive property with an electrode and which can be dissolved in an organic solvent, an organic light-emitting diode including an organic layer including the hyperbranched polymer, and a method of manufacturing the organic light-emitting diode. With the hyperbranched polymer, an organic light-emitting diode having good electrical properties can be produced. An organic layer including the hyperbranched polymer can be formed by a simple wet process, such as spin coating, under a moisture-free inert gas atmosphere. Thus, it is possible to reduce the time and cost of manufacturing an organic light-emitting diode and to improve the stability of diode manufacture by preventing diode deterioration due to moisture.
2. Description of the Related Art
Organic light-emitting diodes include a pair of electrodes and an organic layer interposed between the electrodes. The organic light-emitting diodes are self-emission devices based on the principle that when current is applied to the electrodes, electrons and holes from the electrodes are combined in the organic layer to emit light. The organic light-emitting diodes have advantages such as lightness, simple constitutional elements, easy fabrication process, superior image quality, and wide viewing angle. In addition, the organic light-emitting diodes can achieve high color purity, can perfectly create dynamic images, and have electrical properties suitable for portable electronic equipment due to low power consumption and low driving voltage.
Generally, organic light-emitting diodes are structured such that an anode is disposed on a substrate, an organic layer, such as a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer, and an electron injection layer, is disposed on the anode, and a cathode is disposed on the organic layer.
For example, a hole injection layer forming material may be PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) (see U.S. Pat. No. 5,300,575).
PEDOT:PSS can be deposited using a wet process such as spin coating, but is a water-soluble material and thus is very vulnerable to moisture. Thus, when a hole injection layer is formed of PEDOT:PSS, impurities such as moisture may be easily contained in the hole injection layer. Since moisture etc. can adversely affect the efficiency and lifetime of an organic light-emitting diode, there is room for improvement in a hole injection layer material.